This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to conduct a placebo-controlled, double-blind and randomized 6 month phase IIb cancer control chemoprevention trial of Bowman-Birk Inhibitor Concentrate (BBIC) in patients with oral leukoplakia (OL). Both clinical and histologic response rate of oral leukoplakia (OL) to BBIC will be evaluated to determine whether chemoprevention can prevent oral cancer in humans.